title: Evolution of phosphorylation-dependent regulation of activation-induced cytidine deaminase.
abstract: Interaction of activation-induced cytidine deaminase (AID) with replication protein A (RPA) has been proposed to promote AID access to transcribed double-stranded (ds) DNA during immunoglobulin light chain and heavy chain class switch recombination (CSR). Mouse AID (mAID) interaction with RPA and transcription-dependent dsDNA deamination in vitro requires protein kinase A (PKA) phosphorylation at serine 38 (S38), and normal mAID CSR activity depends on S38. However, zebrafish AID (zAID) catalyzes robust CSR in mouse cells despite lacking an S38-equivalent PKA site. Here, we show that aspartate 44 (D44) in zAID provides similar in vitro and in vivo functionality as mAID S38 phosphorylation. Moreover, introduction of a PKA site into a zAID D44 mutant made it PKA dependent for in vitro activities and restored normal CSR activity. Based on these findings, we generated mAID mutants that similarly function independently of S38 phosphorylation. Comparison of bony fish versus amphibian and mammalian AIDs suggests evolutionary divergence from constitutive to PKA-regulated RPA/AID interaction.
authors.affiliation: Howard Hughes Medical Institute, The Children's Hospital, Harvard Medical School, and the Immune Disease Institute, 300 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Uttiya
authors.initials: U
authors.lastname: Basu
authors.forename: Yabin
authors.initials: Y
authors.lastname: Wang
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Alt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003564:Cytidine Deaminase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D003641:Deamination; D019143:Evolution, Molecular; D017578:Immunoglobulin Class Switching / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D010802:Phylogeny; D051716:Replication Protein A / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D012694:Serine / Q000378:metabolism; D015027:Zebrafish / Q000378:metabolism*; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
chemical_list: D051716:Replication Protein A; D001224:Aspartic Acid; D012694:Serine; D004247:DNA; D017868:Cyclic AMP-Dependent Protein Kinases; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase